Process and apparatus for producing a neck on a metal container having a closed bottom

ABSTRACT

The invention concerns a process and apparatus for the manufacture of metallic products, principally cartridges, bulbs or other similar articles, having a closed bottom and a neck. In the process according to the invention the workpiece to be shaped is placed in a press and is subjected simultaneously to internal and external pressure by a pressurized fluid such as an hydraulic medium, and the neck-drawing step is carried out in this compressively stressed condition. In the apparatus according to the invention suitable cavities are formed outside and inside of the workpiece for the introduction of the pressure medium, which cavities communicate with the source of the medium, and this medium can be placed under the technologically required pressure.

United States Patent Andrasev et al.

[ Nov. 18, 1975 PROCESS AND APPARATUS FOR PRODUCING A NECK ON A METAL CONTAINER HAVING A CLOSED BOTTOM [75] Inventors: Ivan Andrasev; .Izsef Nmeth, both of Budapest, Hungary [73] Assignee: Novex RT, Budapest, Hungary [22] Filed: July 15, 1974 [21] Appl. No.: 488,763

[30] Foreign Application Priority Data July 13, 1973 Hungary AA-743 [52] US. Cl. 72/55; 72/57; 72/62 [51] Int. CI. B21D 26/04 [58] Field of Search 72/54, 55, 57, 58, 60-62 [56] References Cited UNITED STATES PATENTS 795,020 7/1905 Barthelmes 72/58 887950 5/1908 Lindenborg 72/58 2,407,855 9/1946 Stephens 72/58 3,358,489 12/1967 Hutchins 72/62 3.487.668 l/l970 Fuchs, Jr. 72/55 Primary Exanziner-Milton S. Mehr Attorney, Agent, or FirnzYoung & Thompson 57 ABSTRACT The invention concerns a process and apparatus for the manufacture of metallic products, principally cartridges, bulbs or other similar articles, having a closed bottom and a neck.

In the process according to the invention the workpiece to be shaped is placed in a press and is subjected simultaneously to internal and external pressure by a pressurized fluid such as an hydraulic medium, and the neckdrawing step is carried out in this compressively stressed condition.

In the apparatus according to the invention suitable cavities are formed outside and inside of the workpiece for the introduction of the pressure medium, which cavities communicate with the source of the medium, and this medium can be placed under the technologically required pressure.

8 Claims, 1 Drawing Figure U.S. Patent Nov. 18,1975 3,919,871

PROCESS AND APPARATUS FOR PRODUCING A NECK ON A METAL CONTAINER HAVING A CLOSED BOTTOM The invention concerns a process and apparatus for the manufacture of metallic products, principally cartridges, bulbs or other similar articles.

in the manufacture of certain mass-produced metallic products, characteristically cartridges, bulbs etc. it is expedient to start with a semi-finished product having a closed bottom. The fact that the bottom part and the neck part of the final product are made separately, and are then subsequently welded together, results in a manufacturing process of low productivity. If the neck part is made by die-casting and subsequently the bottom part by drawing, a more cumbersome process results which raises more problems than if one starts with a prefabricated semi-finished product having a closed bottom.

The formation of the neck part of the starting prod uct having a closed bottom which product is expedi ently produced by drawing is customarily effected by a multi-stage neck rolling or neck drawing process. Of these two processes multi-stage neck drawing has shown itself to be more expedient, especially for objects of smaller dimensions, e.g., cartridges for soda syphons, I

The drawing process of the neck part of the'closed bottom has to be performed in several stages because the hardening, creasing and possible cracking of the material of the bulb arising in the course of tha change of shape during drawing sets a limit to the reduction, i.e., decrease of cross-section, achievable in one step. This is why theneck drawing operation has to be carried out in several stages and between the individual reductions, i.e., drawing stages, annealing heat treatment steps have had to be interpolated.

As a consequence, the neck-drawing process and thus the current manufacture of cartridge-like products is of low productivity and high costs, even if multi-position, single-purpose machines are used in their production. An additional operation, which increases the overall time required for manufacture, is the step of cutting a thread in the opening of the neck parts of cartridge-like products, necessary for hermetic sealing; this step is performed on a specially-built machine separately from the neck drawing step.

The invention aims to eliminate or at least reduce the above-described drawbacks in the manufacture of cartridges and like metallic products and to render their production more economical. It is recognized that in order to attain this aim it is necessary to create conditions wherein the starting semi-product is rendered more suitable for carrying out the shaping step with a higher deformation factor.

This aim is achieved by the process according to one aspect of the invention by subjecting the starting semiproduct to be shaped simultaneously to internal and external fluid pressure during the neck-drawing step and carrying out the shaping step under these pressurised conditions.

In an advantageous variant of the process according to the invention, the dimensioning of the internal opening of the drawn neck part and the cutting of the internal thread are also effected on the workpiece held in a stamping apparatus with the aid of an exchangeable tool or of another, similar means.

To carry out the process according to the invention a stamping apparatus is employed wherein appropriate cavities are formed for internally and externally sur' rounding, and pressurising, the starting product pre pared for the shaping by means of a pressurised medium, and the apparatus has means for putting the medium under pressure.

In a preferred embodiment of the apparatus according to the invention the pressurisation of the medium surrounding the material to be shaped is effected by the press tool itself during the pressing (stamping) operation.

The invention is described, by way of example only, with reference to the drawing which illustrates a stamping apparatus in longitudinal axial section.

The preferred embodiment of the stamping apparatus according to the invention shown in the drawing consists of three principal parts, a bottom part 1, a central part 2 and an upper part 3.

The bottom part 1 is connected by way of its bottom face and lower cylindrical part to the tool-holding table H of a non-illustrated metalworking machine, or to an automatic rotary indexing table located on the table of the metalworking machine making it possible to perform the neck drawing of several workpieces in a single stroke. On the periphery of the upper portion of the bottom part threaded apertures are disposed for securing the bottom part 1 with the central part 2, while along its centre line a stepped bore is formed for locating and guiding an ejector shaft 4. A central cylindrical bore for the location and guiding ofa movable member 5 is formed in the bottom and central parts 1, 2 which are secured together by bolts, the bore serving to support a workpiece 6 with the cooperation of a piston 7 and a tensioning ring 8 connected thereto. The piston 7 has an arcuately recessed seat in its working face. To

lift the movable member 5 in its unloaded state, springs 9, spring plates 10 and spring-pretensioning screws 11 are located in respective bores in the bottom and central parts 1, 2. The workpiece 6 is positioned at the upper part of the central bore of the movable member 5 in the cavity of the piston and is surrounded in a space 12 by a pressure medium (which may be pneumatic but is preferably an hydraulic medium) communicating with the outside via a bore 13.

A necking ring 14 is disposed in the upper part 3 of the press tool. The hydraulic medium is introduced into and removed from an inner cavity 15 of the workpiece 6 via a bore 16. Hermetic sealing between the end faces of the central and upper parts 2, 3 and between the movable member 5 and the piston 7 is provided by respective seals 17, 18.

The process according to the invention is carried out on the stamping machine described above in the following manner.

The workpiece 6 is placed, expediently by a nonillustrated automated device, in the seat formed in the piston 7 via the gap between the bottom and upper parts 1, 3 which have been pulled apart by the metalworking machine. Then the bottom and upper parts 1, 3 of the machine are closed; the space 12 surrounding the workpiece 6 is hermetically sealed by the seal 17. A hydraulic feeding apparatus (not shown) fills the spaces 12 and 15 around and in the workpiece, respectively, by way of bores 13 and 16. Thereafter, the upper part 3 and thus the necking ring 14 and the movable member 15, descend. In the course of this, the space for the hydraulic medium surrounding and filling the workpiece is reduced, i.e., the hydraulic medium is put under pressure inside and outside the workpiece so that a compressive stress is set up in the workpiece. During the stamping stroke, the pressure of the hydraulic medium is kept constant by a non-illustrated control device which is located in the ducting of the hydraulic medium, is adjusted to the prescribed pressure and the connections of which are shown by arrows adjacent the bores 13 and 16. The deformability of the workpiece increases under pressure and the necking ring 14 performs the neck drawing in a single step. The stamping machine then parts the bottom and top parts 1, 3 from each other. Thereafter expediently by means of a non-illustrated automatic device the workpiece is lifted out, after appropriate movement to remove from it the hydraulic medium required for the shaping. The springs 9 lift the movable member back to its initial position.

In an expedient mode of carrying out the process according to the invention the thread cutting in the opening of the necked part of the workpiece 6 is carried out by a thread borer 19 in the same workholding step as the necking, i.e., the workpiece needs to be clamped in position only once.

Due to the advantages of the process according to the invention, namely the consolidation of the neck drawing process into a single step and the combination of the neck drawing and thread cutting in a single workholding operation, the productivity of the manufacture of cartridge-like products is vastly increased. The economy of production creates the conditions for the manufacture of e.g.', disposable (throw-away) syphon cartridges.

We claim:

1. A process for the production of a neck on a metal container having a closed bottom, comprising placing a metal container having a closed bottom in a press with the closed bottom of the metal container supported by the press, subjecting both the interior and the exterior 4 of the container to the pressure ofa fluid under positive pressure, and while maintaining said positive pressure reducing the internal diameter of the end of said container which is remote from said closed bottom by pressing simultaneously on both ends of the container in opposite directions lengthwise of the container.

2. A process as claimed in claim 1, and forming said neck in a single said pressing operation.

3. A process as claimed in claim 1, and disposing a thread borer in said neck to form an internal thread on said neck while said container is held in said press.

4. Apparatus for forming a neck on a metal container having a closed bottom, comprising a press having therein a piston that bears against the closed bottom of the container, a ring spaced from the piston and having an internal diameter less than the greatest internal diameter of the container to form said neck on said container, means for moving said ring and piston toward each other, and means for introducing fluid under pressure into said container and into said press externally of said container thereby to permit formation of said neck by a single movement of said ring and piston toward each other.

5. Apparatus as claimed in claim 4, and means for moving said piston axially relative to said press.

6. Apparatus as claimed in claim 4, said press having side walls surrounding and spaced from said container, said ring being movable relative to said side walls, and means sealing said ring fluidtightly with said side walls when said ring and piston move toward each other.

7. Apparatus as claimed in claim 4, the bottom of the container being semi-cylindrical and the piston having a semi-cylindrical seat that receives the bottom of the container.

8. Apparatus as claimed in claim 4, and a thread cutting tool reciprocable into and out of the press axially of the container. 

1. A process for the production of a neck on a metal container having a closed bottom, comprising placing a metal container having a closed bottom in a press with the closed bottom of the metal container supported by the press, subjecting both the interior and the exterior of the container to the pressure of a fluid under positive pressure, and while maintaining said positive pressure reducing the internal diameter of the end of said container which is remote from said closed bottom by pressing simultaneously on both ends of the container in opposite directions lengthwise of the container.
 2. A process as claimed in claim 1, and forming said neck in a single said pressing operation.
 3. A process as claimed in claim 1, and disposing a thread borer in said neck to form an internal thread on said neck while said container is held in said press.
 4. Apparatus for forming a neck on a metal container having a closed bottom, comprising a press having therein a piston that bears against the closed bottom of the container, a ring spaced from the piston and having an internal diameter less than the greatest internal diameter of the container to form said neck on said container, means for moving said ring and piston toward each other, and means for introducing fluid under pressure into said container and into said press externally of said container thereby to permit formation of said neck by a single movement of said ring and piston toward each other.
 5. Apparatus as claimed in claim 4, and means for moving said piston axially relative to said press.
 6. Apparatus as claimed in claim 4, said press having side walls surrounding and spaced from said container, said ring being movable relative to said side walls, and means sealing said ring fluidtightly with said side walls when said ring and piston move toward each other.
 7. Apparatus as claimed in claim 4, the bottom of the container being semi-cylindrical and the piston having a semi-cylindrical seat that receives the bottom of the container.
 8. Apparatus as claimed in claim 4, and a thread cutting tool reciprocable into and out of the press axially of the container. 